Characteristics of Residential Tracker Accuracy in Quantified Direct Beam Irradiance and Global Horizontal Irradiance

M S. Sabry; B W. Raichle

doi:10.6000/1929-6002.2014.03.02.2

Authors

M S. Sabry Department of Technology and Environmental Design, Appalachian State University, Boone, NC 28608, USA
B W. Raichle Department of Technology and Environmental Design, Appalachian State University, Boone, NC 28608, USA

DOI:

https://doi.org/10.6000/1929-6002.2014.03.02.2

Keywords:

Solar Tracker, Accuracy, Tracking Error, Non Algorithm Based, Solar Tracking Angles.

Abstract

An accurate solar tracker matches array angles with solar angles throughout the day. Many studies have used the power produced by a tracked PV array as a proxy to characterize a tracker’s accuracy. However, it is difficult to decouple the effects of tracker performance from other effects on power output. It was not found in the literature reviewed that there are studies that determine the accuracy of solar trackers by directly measuring the tracker angles. This study was an experiment to determine the accuracy of two small commercially available non-algorithm based solar trackers: the Zomeworks UTR-020 passive one axis solar tracker, and the Wattsun AZ-225 active electro-optical two axis solar tracker. Accuracy of the trackers was determined by measuring the tracking angles under varying conditions including direct beam irradiation (DBI) and global horizontal irradiance (GHI), and comparing to calculated sun angles. The results showed that the average azimuth angle accuracy of the Zomeworks UTR-020 is 75%, the average azimuth angle accuracy of the Wattsun AZ-225 is 88%, and the average elevation angle accuracy of the Wattsun is 89%. In addition, the results showed a weak correlation between the azimuth accuracy of the Zomeworks and DBF, a strong correlation between the azimuth accuracy of the Wattsun and DBF, and a moderate correlation between the elevation accuracy of the Wattsun and DBF. Moreover, the azimuth accuracy of the Wattsun was always higher than that of the Zomeworks under all DBF and GHI conditions.

References

Mousazadeh H, Keyhani A, Javadi A, Molli H, Abriana, K, Sharifi A. A review of principle and sun-tracking methods for maximizing solar systems output. Renewable and Sustainable Energy Reviews 2009; 13(8): 1800-18. http://dx.doi.org/10.1016/j.rser.2009.01.022 DOI: https://doi.org/10.1016/j.rser.2009.01.022

Clifford MJ, Eastwood D. Design of a novel passive solar tracker. Solar Energy 2004; 77(3): 269-80. http://dx.doi.org/10.1016/j.solener.2004.06.009 DOI: https://doi.org/10.1016/j.solener.2004.06.009

Robinson J, Raichle B. Performance comparison of fixed, 1-, and 2- axis tracking systems for small photovoltaic systems with measured direct beam fraction. In: Appalachian State University. Proceedings of the World Renewable Energy Forum, WREF2012, 13-17 May 2012, Denver, CO, USA. Boulder, Colorado; 2012. Available from http://tec.appstate.edu/sites/tec.appstate.edu/files/pv%20tracking%20system%20performance%20and%20direct%20beam%20robinson%20raichle.pdf

Renewable Energy World. Technology Fundamentals: The Sun as an Energy Resource: The angles to define the position of the sun and the orientation of the tilted plane [image]. http://www.volker-quaschning.de/articles/ fundamentals1/index_e.php (accessed May 2003).

GoGreenSolar [homepage on the internet]. Solar Tracker: Zomeworks Track Rack UTR020 Universal Solar Tracker, 20 Sq. Ft. [image]. Placentia, CA, USA: Gigawatt, Inc.; c2006-2014: Available from http://www.gogreensolar.com/ products/zomeworks-track-rack-utr020-universal-solar-tracker-20-sq-ft

Michalsky J. The astronomical almanac's algorithm for approximate solar position (1950–2050). Solar Energy 1988; 40(3): 227-35. http://dx.doi.org/10.1016/0038-092X(88)90045-X DOI: https://doi.org/10.1016/0038-092X(88)90045-X

Reda I, Andreas A. Solar position algorithm for solar radiation applications. Solar Energy 1988; 76(5): 577-89. http://dx.doi.org/10.1016/j.solener.2003.12.003 DOI: https://doi.org/10.1016/j.solener.2003.12.003

Stafford B, Davis M, Chambers J, Martinez M, Sanchez D. Tracker accuracy: Field experience, analysis, and correlations with meteorological conditions. Proceedings of the 34th Photovoltaic Specialists IEEE Conference, PVSC2009, June 2009. Available from http://ieeexplore.ieee. org/xpl/login.jsp?tp=&arnumber=5411362&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D5411362 DOI: https://doi.org/10.1109/PVSC.2009.5411362